Muzzle velocity compensating device



Nov. 26, 1963 c w. MUSSER 3,111,882

MUZZLE VELOCITY COMPENSATING DEVICE Filed July 5, 1961 INVEN TOR. C WALTON MUSSER ATTO RNEYSI United States Patent Army Filed July 5, 1961, Ser. No. 122,043 3 Claims. (Cl. 89-14) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to muzzle velocity compensating devices such as are useful in equalizing the muzzle velocity of different projectiles fired from the same gun barrel. One important use of this device is in connection with a spotting rifle which is utilized to gage the distance of a target before the firing of the major weapon. In this use, it is highly desirable to have uniformity of performance. Up to the present time, variations in the performance have had a maximum spread of 160 feet per second. While such variations are very objectionable, they have had to be accepted due to the inability sufficiently to control all the parameters in the manufacture of the gun and ammunition.

The present invention minimizes these undesirable variations by the provision of means for regulating the gas pressure to the rear of the projectile as it travels through the gun barrel, this regulation being effected by the recoil force of the barrel. For the device to function effectively, it is necessary that the gun be freely recoiling during the time the projectile is in the barrel. Since there is a definite relationship between the weights of the gun and the projectile, the recoil velocity of the gun bears a direct relationship to the velocity of the projectile. As will appear, this relationship is utilized to regulate the muzzle velocity of the projectile.

The invention will be better understood from the following description when considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

FIG. 1 illustrates a preferred form of the invention, and

FIGS. 2 to 6 are explanatory diagrams relating to the operation of the gun shown in FIG. 1.

In FIG. 1, at spotting rifle is shown as having a barrel 10 which is attached to the barrel 11 of a major gun by means of brackets 12 and 13. As is well known, the bushing in bracket 12 may have a spherical bearing to allow angular adjustment and the bracket 13 may include a mechanism for elevating and traversing the spotting rifle. Such a bearing and mechanism is disclosed by U. S. Patent 2,949,825.

The muzzle velocity compensating device includes a collar 14 which is fixed to the barrel 10, a bushing 15 which encircles and guides this barrel, and a spring 16 which surrounds the barrel and interconnects the collar 14 and the bushing 15.

The section of the rifle barrel encircled by the bushing 15 is perforated as indicated by FIGS. 2 to 5.

The static condition of the device is indicated by FIG. 2 where all the perforations are covered by the bushing 15.

3,1 1 1,882 Patented Nov. 26, 1963 In FIG. 3, the spotting rifle is assumed to have fired a projectile I7 which has a normal muzzle velocity and provides a normal recoil force 18. This force moves this rifie barrel It) rearwardly and compresses the spring 6 to a point where one half the perforations in the rifle barrel I0 are uncovered and the area under the pressure travel curve A of FIG. 6 is a measure of the projectile velocity.

FIG. 4 represents the situation where the spotting rifle has fired a projectile 19 which, with half the perforations uncovered, would have a lower than normal muzzle velocity. This may be from a lower pressure such as that represented by the first portion of curve B of FIG. 6 The firing of the projectile I9, however, produces a recoil force 26 which is effective to uncover only one third of the perforations. This, then, releases a smaller quantity of gas through the perforations and maintains the gas pressure at a value high enough to produce the same area under the curve and impart a normal muzzle velocity to the projectile.

In FIG. 5, the spotting rifle is assumed to have fired a projectile 21 which, with half the perforations uncovered, would have a higher than normal muzzle velocity. This may be from a higher pressure such as that repre sented by the first portion of curve C of FIG. 6. The recoil force 22 produced by the firing of this projectile uncovers two thirds of the perforations thus reducing the gas pressure over the last portion of curve C to a point such that the area under the curve C is equal to that of curve A and the projectile has a normal muzzle velocity.

While the muzzle velocity compensating device of the present invention has been described as applied to a spotting rifle, it is obviously applicable to different types of guns, due considerations being given in each particular case to the relation between the weight of the gun and projectile, to the size of the spring and to the number of perforations.

The basic parameter to be considered is the recoil velocities in relation to the distance to be travelled to uncover or open the perforations. It should be so designed that during the first portion of the pressure travel curve the rifie is essentially firing as a normal unvented rifle. Then any excess pressure from the firing charge will produce a higher rifle recoil velocity and hence will open more perforations. This tends to vent more gases and alter the last half of the pressure time curve so that the total area under this curve will be constant for a wide range of powder burning characteristics. Obviously, dif- 'ferent rifle/bullet weight rations will require different venting arrangements. The one shown is intended to be diagrammatic to most fully explain the intended operation.

I claim:

1. In a gun, the combination of a barrel support, a barrel extending through said support and having a collar spaced forwardly therefrom, said barrel having a perforated area, and means extending between said support and said collar for biasing said barrel to a position where said perforated area is covered by said support whereby said perforated area is moved outside said support to an extent determined by the recoil incident to the firing of said gun.

2. A combination according to claim 1 wherein said biasing means is a spring having a stiffness so related to the mass of said barrel that said perforated area is uncovered to an extent determined by the recoil incident to the firing of said gun.

3. In means for equalizing the range of a gun firing projectiles having different Weights, the combination of a support, a gun barrel extending through said support and having a perforated area substantially coextensive therewith, a collar fixed to said barrel forwardly of said support, and a spring extending between said support and said collar and biasing said barrel to a position Where said perforations are covered by said support, said spring having a resilience such that said perforations are moved out of said support to an extent dependent on the weight of the projectile fired from said gun.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A GUN, THE COMBINATION OF A BARREL SUPPORT, A BARREL EXTENDING THROUGH SAID SUPPORT AND HAVING A COLLAR SPACED FORWARDLY THEREFROM, SAID BARREL HAVING A PERFORATED AREA, AND MEANS EXTENDING BETWEEN SAID SUPPORT AND SAID COLLAR FOR BIASING SAID BARREL TO A POSITION WHERE SAID PERFORATED AREA IS COVERED BY SAID SUPPORT WHEREBY SAID PERFORATED AREA IS MOVED OUTSIDE SAID SUPPORT TO AN EXTENT DETERMINED BY THE RECOIL INCIDENT TO THE FIRING OF SAID GUN. 